JortS29 is right on the money. Pixel pitch is really only significant when viewing at the pixel level. However, as photogaphers, we must extract the art from the science and make comparisons at a viewing or print level. If you compare the A700 and A900 at the pixel level, their noise is similar. However, whether you print at 20"x30," or make a 600x900 web image, the A900 has quite a noise advantage, and that is a more relevant comparison.